Italian definite articles (singular)

il

la

l'

lo

il: is used when the noun is a masculine noun starting with a consonant

e.g. succo = juice, a masculine noun

thus, il succo

la: is used when the noun is a feminine noun starting with a consonant

e.g. pasta, feminine noun

thus, la pasta

l': is used when the noun starts with a vowel, regardless masculine or feminine

e.g. aglio = garlic, masculine noun starting with a vowel

e.g. acqua = water, feminine noun starting with a vowel

thus, l'aglio, l'acqua

lo: is used when the noun is a masculine noun starting with "s" + consonant or "z"

e.g. zucchero = sugar, masculine starting with a "z"

e.g. sport = sport, masculine nouns starting with s + p (s + a consonant)

thus, lo zucchero, lo sport